Filter and filter cartridge

ABSTRACT

A filter cartridge for a filter for filtering a fluid is to be used downstream of a main filter cartridge in a filter and is provided with an inflow surface, an outflow surface, and a main flow direction extending from the inflow surface to the outflow surface. A filter body is provided that can be flowed through along the main flow direction. A filter cartridge frame supports the filter body. A seal is disposed on the filter cartridge frame and separates a filter interior of a filter into a clean side and a raw side. An adhesive connection is provided that connects the filter body and the filter cartridge frame to each other. In one configuration, the filter cartridge frame at an inflow side is provided with a grip area, wherein the grip area enables inflow of a fluid into the filter body via the grip area and manual removal of the filter cartridge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of internationalapplication No. PCT/EP2015/063592 having an international filing date of17 Jun. 2015 and designating the United States, the internationalapplication claiming a priority date of 18 Jun. 2014, based on two priorfiled German patent applications Nos. 20 2014 004 897.5 and 20 2014 004894.0, and a priority date of 11 Nov. 2014, based on prior filed Germanpatent application No. 20 2014 008 899.3, the entire contents of theaforesaid international application and the aforesaid three Germanpatent applications being incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention concerns a filter, in particular for internalcombustion engines, for filtering a fluid, in particular air, as well asa filter cartridge, in particular for such a filter.

In particular in construction and agricultural machines, engine airfiltration is becoming more and more important. On the one hand, moreand more efficient air filters are used because higher engineperformances and stricter emissions standards require an increased airthroughput through the engine. On the other hand, the number ofcomponent groups that are installed by default, such as air-conditioningdevices, increases. This reduces the available installation space in thevehicle. Finally, there is the desire to design vehicles smaller andmore lightweight which also is done at the expense of the availableinstallation space.

In case of the easing integration, a particularly high reliability ofeach component of such a filter is important for long servicingintervals. In the aforementioned fields of use, aside from the highfluid throughput, also high mechanical loads, for example, byvibrations, require a particularly stable construction of the totalsystem.

It is an object of the invention to provide a filter cartridge, inparticular a secondary element, that as a result of a robustconstruction provides particularly high reliability.

In addition to the outer dimensions of an air filter, the maximumpossible air throughput, and the service life of a filter, the pressureloss that is caused by the air filter is a decisive parameter in regardto evaluation of the performance of an air filter.

It is a further object of the invention to configure the pressure lossof a filter cartridge for a filter with a given outer geometry as low aspossible.

The aforementioned objects are solved respectively by different aspectsof the embodiments of a filter to be described in the following, inparticular for internal combustion engines, for filtering a fluid, inparticular air, as well as a filter cartridge, in particular for such afilter. As can be seen in the embodiments, the different aspects can beprovided advantageously individually or combined in embodiments wherein,in case of combination, individual aspects enhance the advantages ofother aspects and a synergistic interaction leads to an advantageousproduct.

SUMMARY OF THE INVENTION

The object is solved by a filter cartridge, in particular secondaryfilter cartridge, for a filter for filtering a fluid, in particular air,in particular for an internal combustion engine, in that the filtercartridge is designed to be inserted downstream of a main filtercartridge into a filter and comprises an inflow surface, an outflowsurface, and a main flow direction, a filter body that can be flowedthrough along the main flow direction, a filter cartridge framesupporting the filter body, wherein the filter cartridge frame comprisesa seal for separation of a filter interior of a filter into clean sideand raw side and comprises an adhesive connection between the filterbody and the filter cartridge frame.

Further embodiments of the invention are disclosed in the dependentclaims.

The secondary filter cartridge according to the invention is designed tobe inserted downstream of a main filter cartridge into a filter. Itcomprises an inflow surface, an outflow surface, and an outflowdirection. Moreover, the secondary filter cartridge comprises a filterbody which can be flowed through along the outflow direction and afilter cartridge frame supporting the filter body. The filter cartridgeframe comprises a seal for separating a filter interior of a filter inclean side and raw side as well as an adhesive connection between thefilter body and the filter cartridge frame. The separate configurationof seal and adhesive connection enables a substantially more stableconfiguration of the adhesive connection.

In a preferred embodiment of the invention, the seal is designed to beacting radially to the main flow direction and is extendingcircumferentially about the secondary filter cartridge in particularsubstantially perpendicular to the main flow direction. The seal cancomprise a cellular rubber.

Particularly preferred, it is provided that a support section of thefilter cartridge frame is extending circumferentially about the filterbody and the support section comprises on the inner side an inner edge,in particular a groove, for receiving an adhesive material of theadhesive connection. This enables a mechanically particularly stableconnection between the filter body and the filter cartridge frame. Inparticular, it can be provided that the depth of the groove extends inthe direction of the main flow direction.

In a further embodiment of the invention, a seal receiving section ofthe filter cartridge frame is extending circumferentially externallyabout the filter body. In particular when removing and installing thesecondary filter cartridge, shearing forces acting on the seal areabsorbed by the seal receiving section.

One embodiment provides that the adhesive connection comprises apolyurethane and in particular is foamed. In particular, the adhesiveconnection can penetrate the filter body partially and, in this way, canensure a particularly strong adhesive connection between filter body andfilter cartridge frame.

In a further embodiment of the invention, it can be provided that thefilter cartridge frame comprises at the outflow side a grate that iscovering the outflow surface. This increases the collapse resistance ofthe secondary filter cartridge at high differential pressures. Inparticular, the grate can be formed as one part together with the filtercartridge frame.

In one embodiment of the filter cartridge, in particular secondaryfilter cartridge, which represents also its own invention, it isprovided that the filter cartridge comprises a main inflow surface, anoutflow surface, and a main flow direction. Moreover, the filtercartridge comprises a filter body which can be flowed through along themain flow direction, as well as a filter cartridge frame supporting thefilter body. The filter cartridge frame comprises preferably a seal forseparating a filter interior of a filter in clean side and raw side aswell as preferably a grip area at the inflow side. The grip area isdesigned further preferred such that an inflow into the filter body viathe grip area and a manual removal of the filter cartridge are possible.In this way, the area is enlarged by means of which inflow into thefilter body is realized. Since in general there must be provided anywaya possibility for manual handling the filter cartridge, in particularfor installation and removal of the filter cartridge, the pressure dropor pressure loss caused by the filter cartridge is significantly reducedby designing the grip area so as to be flowed through by the fluid to befiltered.

In a preferred further embodiment of the invention, it is provided thatlaterally to the main inflow surface an auxiliary inflow surface isprovided. This provides for the generally improved inflow situation ofthe filter cartridge with a further inflow surface of the filtercartridge and reduces thus the pressure loss caused by the filtercartridge further. In this context, it can be particularly provided thatthe grip area enables inflow into the filter body laterally adjacent tothe main inflow surface.

Preferably, the grip area is designed as a grip depression and the gripdepression is facing toward the filter body. On the one hand, the gripdepression provides a particularly simple possibility for removing thefilter cartridge from its inserted position. On the other hand, theshape of a depression enables a particularly turbulence-free inflow ofthe fluid to the filter body, in particular to the main inflow surfaceand the auxiliary inflow surface.

In one embodiment of the invention, it is provided that in main flowdirection the grip area is substantially not projecting past the inflowsurface. Also, the filter body can be substantially of aparallelepipedal shape.

In a further configuration, the filter body is configured aszigzag-shaped folded filter bellows and in particular one of the endfaces of the filter bellows folds (i.e., the side faces which are formedby the zigzag-shaped course of the folded filter medium) face in thedirection of the grip area. Due to the configuration according to theinvention of the grip area that is open toward this end face, theflowing fluid is guided to the end faces of the filter bellows folds. Incase of a one-sided sealing action of the end faces only at the cleanside of the folded filter medium, the end face partially remains open atthe raw-side unglued gaps between the folds. In this way, the fluid canflow at the end face into the interior of the filter bellows withoutbypassing the filter body. In this way, in addition to the regular maininflow surface which is formed by the fold edges, the end face of thefilter bellows can serve as an auxiliary inflow surface and can thusminimize the pressure loss.

In a particularly preferred embodiment of the invention, the filtercartridge is designed as a secondary filter cartridge. Since inparticular the installation space which is downstream of the main filtercartridge is particularly tight not always allows for an inflow surfaceat the secondary filter cartridge to be realized to be equivalent to thetotal outflow surface of the main filter cartridge, an additionalauxiliary inflow surface is of particularly great importance foroptimizing the entire filter system.

In a further inventive embodiment of the invention, it is provided thatthe filter cartridge frame at the outflow side is provided with a gratecovering the outflow surface. In particular at high pressuredifferentials or when changing the main filter element in operation, aparticularly high collapse pressure of a secondary filter cartridge isimportant. This is decisively improved by providing an outflow-sidegrate.

The grate can be preferably formed as one part together with the filtercartridge frame.

The filter according to the invention, in particular for internalcombustion engines, for filtering a fluid, in particular air, comprisesa filter housing with a raw-side area and a clean-side area. A mainfilter element is insertable into the filter housing and comprises amain filter element inflow surface, a main filter element flowdirection, a main filter element outflow surface as well as a sealarranged on a sealing surface. For example, the main filter element canhave a prismatic basic shape. In particular, a flow through the lateralfaces can be realized. The seal serves for fluid-tight separation of theraw-side area of the filter housing from the clean-side area of thefilter housing. Moreover, the filter comprises a secondary filterelement arranged downstream of the main filter element and provided witha secondary filter element inflow surface, a secondary filter elementflow direction, and a secondary filter element outflow surface. Thesealing surface is positioned at a slant to the main flow direction ofthe main filter element. The slanted sealing surface makes availablewithin the filter housing downstream of the main filter element a spacein which, on the one hand, the secondary filter element can be arranged.At the same time, due to the sealing surface positioned at a slantrelative to the main flow direction, a deflection of the main flowdirection is already realized in the filter housing. Accordingly, with asuitable arrangement of an outflow opening on the filter housing, adeflection of the fluid flow in the desired direction can be realized.It is thus possible to eliminate the otherwise required pipe elbow orthe like downstream of the housing.

The sealing surface and the main flow direction can be positioned inparticular at an angle that is between 85° and 10°. Within this anglerange, a noticeable deflection of the fluid flow occurs.

One embodiment of the invention provides that the sealing surface iscurved and in particular is positioned on a lateral cylinder surface. Bymeans of a concave configuration of the sealing surface, viewed from themain filter element, the installation space available for the mainfilter element can be optimized and provides sufficient space for asecondary element with a suitable selection of the radius of curvature.At the same time, due to the curvature of the sealing surface, theoutflow direction of the filter housing, depending on the position ofthe outflow opening, can be determined in a particularly simple way.Preferably, the axis of the cylinder of the lateral cylinder surface isperpendicular to the main filter element flow direction andperpendicular to the secondary filter element flow direction.

Alternatively, the sealing surface can be positioned in a plane.

A preferred embodiment of the invention provides that the sealingsurface and the main filter element outflow surface extend parallel. Inthis way, a clearly defined separation plane between the raw side andthe clean side of the filter housing is provided. At the same time, fora curved embodiment of the sealing surface, an installationspace-optimized configuration of the filter interior and thus of theentire filter is provided.

Preferably, it is provided that the secondary element inflow surface isextending parallel and spaced-apart relative to the sealing surface. Inthis way, it is ensured that upon change of the secondary filter elementthe clean side of the filter housing does not become soiled. In a curvedconfiguration of the sealing surface, a secondary element inflow surfaceis provided that is also curved.

In a preferred embodiment of the invention, the basic shape of thesecondary filter element is a parallelepiped. This enables a simpleconstruction of the secondary element, for example, from a flat elementwith straight folds in which the fold edges at the inflow side andoutflow side each form planes that are preferably positioned parallel toeach other at a spacing defined by the fold height.

Alternatively, the basic shape of the secondary element can be a prismwith one or several curved lateral faces such as, for example, a hollowlateral cylinder sector. This can be realized, for example, by a curvedflat bellows. This shape provides the possibility of adapting thesecondary filter element to a curved main filter element outflow surfaceand to thereby further optimize the installation space.

In a preferred embodiment of the invention, the basic shape of the mainfilter element is a prism. In particular, the base face and the top faceof the prism can be a quadrangle or a pentagon. The quadrangle or thepentagon can have two or three right angles, an acute and an obtuseangle. A preferred embodiment of the invention provides that a lateralface of the prism, viewed from the exterior, is convexly curved so thata main filter element outflow surface results which is embodied as alateral cylinder surface, for example.

An advantageous embodiment of the invention provides that the mainfilter element is a folded bellows with at least two different folddepths. By means of two different fold depths, the main filter elementoutflow surface that is slanted relative to the main flow direction ofthe main filter element can be realized at the fold end faces.Alternatively, by a continuously increasing fold height, the main filterelement outflow surface that is slanted relative to the outflowdirection of the main filter element can be realized at the fold edges.The terms fold depth and fold height are synonymously used herein.

An advantageous embodiment of the invention provides that the filterhousing has an inflow direction, an outflow direction, as well as anoutflow area with an outflow opening. An outflow socket can be attachedto the outflow area wherein the outflow area comprises a fasteningsurface for the outflow socket and the fastening surface is positionedat an angle of 45° relative to the main filter element flow direction.The fastening surface which is slanted by 45° relative to the main flowdirection is located particularly preferred in an arrangement on thefilter housing in such a way that it is positioned, viewed in the mainfilter element flow direction, within the filter housing, i.e., it doesnot project past it. At the same time, this fastening surface, viewed ina direction perpendicular to the main flow direction of the main filterelement, i.e., for example, in an insertion direction of the main filterelement, is located below the main filter element. An outflow socketwhich is mounted on this fastening surface can now distribute theoutflowing filtered fluid comparatively easily in any directions.

A particularly preferred embodiment of the invention provides that theoutflow socket is formed such that a deflection of the flow direction by45° results. In this way, only the orientation of the outflow socket onthe outflow area, in particular on the fastening surface, is relevantwith respect to the final outflow direction. This enables in aparticularly advantageous way the determination of the outflow directionof the filtered fluid with a single component, i.e., the outflow socket.The final outflow direction of the filter housing results by suitableorientation of the outflow socket on the fastening surface.

A preferred further embodiment of the invention provides that theoutflow socket comprises a rotation-symmetrically embodied fasteningarea for attachment on the fastening surface of the filter housing.Accordingly, by rotation of the outflow socket the final determinationof the outflow direction of the entire filter housing can be determined.In this way, an angle range between 0° and 90° results between theinflow direction of the filter housing and the outflow direction of thefilter housing with one and the same components.

In the same way, it can be determined that the outflow direction and thefastening surface are positioned at an angle of 45° relative to eachother.

An alternative further embodiment of the concept of the inventionprovides that the fastening surface is positioned on a lateral cylindersurface. The axis of the cylinder is positioned in this contextpreferably perpendicular to the main flow direction of the main filterelement. Such a curved fastening surface is preferably combined with acorrespondingly curved fastening area of an outflow socket. The positionof the outflow socket at the outflow area then determines the outflowdirection of the filter housing.

Preferably, the fastening surface and the secondary element outflowsurface extend parallel. This enables an extremely high integration andthus installation space optimization.

According to the invention, in an embodiment it can be provided that themain filter element is insertable along an insertion axis into thefilter housing and removable, wherein the insertion axis is positionedrelative to the main flow direction at an angle between 90° and theangle at which the sealing surface and the main flow direction arepositioned relative to each other. According to this embodiment, thefilter housing has a cover that is designed such that, in the state inwhich it closes off the filter housing, it exerts a force on the mainfilter element in the direction of the sealing surface. Due to theslanted position of the sealing surface, the force is at least partiallyconverted into an axial force, i.e., into a force which is acting in thedirection of the main flow direction. This provides a force whichpresses the main filter element with its seal mounted on the sealingsurface against a main filter element seat on the filter housing.

The main filter cartridge comprises an inflow surface, an outflowsurface as well as a main flow direction, a filter body and a filtercartridge frame, in particular exchangeable, that supports. The filtercartridge frame comprises in the area of the outflow surface a seal forseparating a filter interior in clean side and raw side and a spacerstructure for determining a spacing between the filter cartridge frameand a further filter cartridge that can be positioned downstream in themain flow direction. By means of the spacer structure, a priordetermined spacing between filter cartridge, that can be, for example, amain filter cartridge, and a downstream arranged further filtercartridge, that can be, for example, a secondary filter cartridge, canbe maintained even under extreme conditions of use, for example,vibrations. This ensures that the further filter cartridge cannot moveout of its designated position and thereby lose its sealing function andsecuring function.

In one embodiment of the invention, it is provided that the spacerstructure is arranged within the seal, in particular at severallocations along the seal, and in particular at the circumference of theoutflow surface. For such a configuration it can be provided that theouter circumference perpendicular to the main flow direction of thefurther filter cartridge follows in shape and size the seal andtherefore provides a support surface for the spacer structure.

An advantageous embodiment of the invention provides that the outflowsurface or/and of a sealing surface of the seal are positioned relativeto the main flow direction at an angle between 5° and 45°, in particularan angle of 24°±10° and in particular an angle of 24 °±5°. An outflowsurface which is angled in such a way to the main flow direction has alarger surface area compared to the outflow surface. Generally, theangled arrangement of the outflow surface or/and of the sealing surfaceprovides the possibility of effecting a deflection of the main flowdirection already within the filter cartridge or directly downstream ofthe filter cartridge. This saves installation space and improves thepressure loss within the filter as a result of shorter flow distances.

Advantageously, the spacer structure is formed integrally with the seal,in particular is molded with the seal. This enables, for example, theuse of the same material and manufacture of the spacer structure in thesame processing step used for the seal.

A particularly preferred embodiment provides that the spacer structureis designed to exert in the installed state of the filter cartridge aclamping or holding force on a further filter cartridge which can bearranged downstream in the main flow direction, in particular asecondary filter cartridge, wherein the force presses the further filtercartridge into its installation position. This can be achieved, forexample, in that the spacer structure is made of an elastic material.When the filter cartridge is then inserted after the further filtercartridge, already the insertion can exert a force on the further filtercartridge by suitable selection of an appropriate geometry. Thisimproves, in turn, the reliability of the filter because the furtherfilter cartridge is permanently exposed to a force which keeps it in itsdesignated position.

In a preferred embodiment of the invention, the seal acts axially in thedirection of the main flow direction. This means that the force which isto be applied for the sealing action is extending parallel to theoutflow direction.

In an embodiment of the invention, the filter body is embodied as afilter bellows, in particular with variable fold height. By means of thevariable fold height, for example, an outflow surface that is extendingat a slant to the main flow direction can be realized. A configurationof a zigzag-shaped folded filter body is understood as variable foldheight when the fold heights across a length of the folded bellowsdefined by the sequence of fold edges is not constant but changescontinuously or discontinuously or differs in neighboring sections.Preferably, the height of the folds changes continuously, and furtherpreferred linearly, across the length of the bellows.

The object is solved also by a filter for filtering a fluid, inparticular air, in particular for an internal combustion engine. Thefilter according to the invention comprises a filter housing into whicha main filter cartridge and a secondary filter cartridge can beinserted. The main filter cartridge comprises an inflow surface, anoutflow surface as well as a main flow direction, a filter body and afilter cartridge frame supporting the filter body. The secondary filtercartridge can be arranged downstream of the main filter cartridge. Thefilter cartridge frame comprises in the area of the outflow surface aseal for separating the filter housing in raw side and clean side aswell as a spacer structure for determining a spacing between the filtercartridge frame and the secondary filter cartridge.

In an embodiment of the filter according to the invention, it isprovided that the filter housing has an insertion direction which issubstantially perpendicular to the main flow direction. This enablesafter insertion of the secondary filter cartridge an insertion of themain filter cartridge in such a way that the secondary filter cartridgeis blocked against moving out of its designated seat.

In a preferred embodiment, it is provided that the secondary filtercartridge comprises a seal for contacting the filter housing wherein theseal is in particular designed to be radially acting relative to theflow direction of the secondary filter cartridge. It is thus notrequired to provide a sealing surface on the filter housing in axialextension of the main flow direction of the secondary filter cartridge.Instead, already upon insertion into the designated seat, the seal iseffective perpendicular to the main flow direction against the filterhousing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail with reference to thedrawings.

FIG. 1 is a perspective section illustration of an embodiment of afilter according to the invention with inserted main filter cartridgeand secondary filter cartridge.

FIG. 2 shows the filter of FIG. 1 without inserted secondary filtercartridge.

FIG. 3 shows the filter of FIG. 1 without inserted main filtercartridge.

FIG. 4 shows the filter of FIG. 1 in a cross-sectional view.

FIG. 5 is a perspective external view of the filter of FIG. 1 accordingto the invention.

FIG. 6 is a perspective view of a secondary filter cartridge accordingto the invention with filter body.

FIG. 6a is a perspective view of an alternative secondary filtercartridge filter body according to the invention.

FIG. 7 is a perspective view of the secondary filter cartridge of FIG. 6without filter body.

FIG. 8 is another perspective view of the secondary filter cartridge ofFIG. 6 without filter body.

FIG. 9 is a perspective section view of the filter of FIG. 6.

FIG. 10 is a section view of the filter of FIG. 7.

FIG. 11 is a perspective front view of a main filter cartridge.

FIG. 12 is a perspective rear view of the main filter cartridge of FIG.11.

FIG. 13 is a perspective section view of the main filter cartridge ofFIG. 11.

FIG. 14 shows a perspective rear view of the main filter cartridge ofFIG. 11 without edge protection.

FIG.15 is perspective external view of the filter of FIG. 5 with theoutflow socket in a first position.

FIG.16 is perspective external view of the filter of FIG. 5 with theoutflow socket in a second position.

FIG. 17 shows a side view of the filter of FIG. 5.

FIG. 18 shows a side view of the filter of FIG. 15.

FIG. 19 shows a side view of the filter of FIG. 16.

PREFERRED EMBODIMENTS OF THE INVENTION

With reference to FIGS. 1 through 5, an embodiment of a filter 10according to the invention will now be described. Such a filter 10 canbe used, for example, in an air intake manifold of a construction oragricultural machine, a compressor or another device with an internalcombustion engine, for filtering a fluid, in particular air. The filter10 comprises a filter housing 12 which can be divided roughly into araw-side area 14 and a clean-side area 16.

The filter 100 is flowed through along a main inflow direction X. On aninflow side 16 the fluid to be filtered impacts on a coarse or apre-separation module 18 which is designed in the present case as acyclone block. In the cyclone block 18, a plurality of individualpre-separation cells 20 are connected in parallel in a so-calledmulti-cyclone block. The dust and/or water that has been pre-separatedin the cyclone block 18 is removed through a discharge socket 22 fromthe filter housing 12.

Downstream of the cyclone block 18, the fluid to be filtered flows intothe main filter cartridge 100. The main filter cartridge 100 is embodiedin the present case as a prism. An inflow surface 110 of the main filtercartridge 100 is not positioned parallel to an outflow surface 112 ofthe main filter cartridge 100. Instead, the inflow surface 110 and theoutflow surface 112 are positioned at an angle to each. In the presentcase, the inflow surface 110 of the main filter cartridge 100 is smallerwith regard to the desired surface area than the outflow surface 112 ofthe main filter cartridge 100. At the outflow side of the main filtercartridge 100, a secondary filter cartridge 200 is provided in thefilter housing 12. A main inflow surface 210 of the secondary filterelement 200 is oriented toward the outflow surface 112 of the mainfilter cartridge 100 and in particular is arranged parallel thereto. Anoutflow surface 212 is oriented in this embodiment parallel to the maininflow surface 210 of the secondary filter cartridge 200. Due to theslanted position of the outflow surface 112 of the main filter cartridge100, already upon inflow of the fluid from the main filter cartridge100, but also upon inflow from the secondary filter cartridge 200, adeflection of the main flow direction X is occurring. Due to the outflowgeometry of the filter housing 12 in the outflow area 24, the flowingfluid is deflected to the outflow direction Y and guided toward anoutflow socket 26. In the present case, the main outflow direction Y issubstantially perpendicular to the main inflow direction X. However,other outflow directions are conceivable also. This will be explained inmore detail particularly in connection with FIGS. 15 to 19.

The main filter cartridge 100 comprises a main filter cartridge inflowsurface 110, a main filter cartridge flow direction X1, a main filtercartridge outflow surface 112 as well as a seal 116 arranged on asealing surface 114 for fluid-tight separation of the raw-side area 14and of the clean-side area 16 of the filter housing 12. A secondaryfilter cartridge 200 with a secondary filter cartridge inflow surface210, a secondary filter cartridge flow direction Y1, and a secondaryfilter cartridge outflow surface 212 is arranged downstream of the mainfilter cartridge 100. The sealing surface 114 of the main filtercartridge 100 is slantedly positioned relative to the main flowdirection Y1 of the main filter cartridge 100. In particular, thesealing surface 114 is positioned at an angle α that is preferablybetween 5° and 45° (see FIG. 4). In particular the angle amounts to24°±10° and 24°±5°. In the present embodiment, the angle α is 24° (seeFIG. 4).

The secondary filter cartridge inflow surface 210 extends substantiallyparallel and at a spacing to the sealing surface 114 of the main filtercartridge 100. The spacing is less than 2 cm; in the present embodiment,the spacing is 1 cm.

FIGS. 11-14 show the main filter cartridge 100. The main filtercartridge 100 comprises an inflow surface 110 and an outflow surface112. Inflow to the main filter cartridge 100 is occurring along a maininflow direction X and flow through it occurs along a main flowdirection X1. The main filter cartridge 100 comprises a filter cartridgeframe 118 that receives a filter body 120. The filter body 120 is in thepresent case designed as a folded bellows. Inflow-side fold edges 122are positioned opposite outflow-side fold edges 124. Inflow-side foldedges 122 and outflow-side fold edges 124 are positioned parallel,substantially perpendicular to the main flow direction X1, andsubstantially horizontally in FIGS. 11-14. This orientation of the foldedges 122, 124 enables a variation of the fold depth in the direction ofan insertion direction Z. Along the insertion direction Z, the mainfilter cartridge 100 is insertable into the filter housing 12 of thefilter 10. In the present embodiment, the fold height is reduced alongthe insertion direction Z. This effects a tilting of the inflow surface110 relative to the outflow surface 112.

In the area of the outflow surface 110, the filter frame 118 has asealing surface 114 along which a circumferentially extending seal 116is provided. The seal serves for separating the raw-side area 14 fromthe clean-side area 16 in the filter housing 12 of the filter 10 whenthe main filter cartridge 100 is inserted into the filter 10. The seal116 comprises substantially a U-shape in cross-section.

For reinforcement and better mechanical connection of the seal 116 tothe filter frame 118, a web 126 is provided which engages the U-shape ofthe seal 116. At the same time, the seal 116 can contact the filter body120 or penetrate it so that an adhesive connection of the filter body120 with the filter cartridge frame 118 and a fluid-tight sealing actionbetween filter body 120 and filter cartridge frame 118 is generated atthe same time.

Moreover, the seal 116 comprises a spacer structure which is embodied inthe present case as support knobs 128. The support knobs 128 arecomponents of the sealing material of the seal 116. As can be seen inthe cross-sectional view of FIG. 4, the support knobs 128 contact thesecondary filter cartridge 200, in particular a secondary filtercartridge frame, when main filter cartridge 100 and secondary filtercartridge 200 are inserted in the filter housing 12 of the filter 10. Inthis state, the secondary filter cartridge 200, even for vibrationexcitation that can be transmitted, for example, through the filterhousing 12, cannot move out of a seal seat in the filter housing 12.Also, by means of the support knobs 128 it is ensured that the secondaryfilter cartridge 200 after installation of the main filter cartridge 100and closure of the cover 13 is seated in the correct position in thefilter housing 12.

A plurality of the support knobs 128 are positioned along the seal 116on the side which is facing the outflow surface 112. They can beproduced, for example, integrally with the seal 116 when producing theseal 116.

The seal 116 is located at the outflow surface 112 of the main filtercartridge 100 and acts in a direction that is perpendicular to theoutflow surface 112, i.e., substantially axially along the main flowdirection X1.

The main filter cartridge 100 comprises at its inflow side 110 an edgeprotection 130 which is extending externally circumferentially about thefilter frame 118. The edge protection 130 is designed such that upontapping of the main filter cartridge 100, for example, for cleaning,impacts against the filter frame 118 can be absorbed and at leastpartially compensated. In this way, breakage of the filter frame 118 orother damages of the filter cartridge 100, for example, of the filterbody 120, can be avoided. The edge protection 130 extendscircumferentially about the inflow-side edge of the filter element 100.In this context, individual interruptions, for example, the notches 134can be provided. The notches 134 are generated when producing the edgeprotection 130. In this context, the filter frame 118 together withfilter body 120 is positioned in a casting mold. Webs secure a spacingbetween the casting mold bottom and the filter body 118 and cause theformation of the notches 134 during the casting process.

Cutouts 136 are provided at the inflow-side edge 132. The cutouts 136penetrate the sidewalls of the filter frame 118 and extend thusperpendicular to the main flow direction X1. During the alreadymentioned casting process, the casting material for the edge protection130 penetrates the cutouts 136, contacts the inner walls of the filtercartridge frame 118 and in particular the filter body 120. In this way,a fluid-tight sealing action between the filter body 120 and the filtercartridge frame 118 and at the same time an adhesive connection of thetwo components is produced. Accordingly, the edge protection 130 ismonolithically produced with the adhesive connection between filter body120 and filter cartridge frame 118 and an also required sealing actionbetween the two components. The edge protection 130 can be produced, forexample, of a foamable polyurethane. However, also silicone-basedmaterial systems are conceivable.

The filter cartridge 100 comprises a grip 138. The grip 138 interactswith the cover 13 of the filter 10 and ensures reliable seating of themain filter cartridge 100 in the filter housing 12 and, at the sametime, exerts pressure directed axially in the direction of the main flowdirection X1 on the seal 116 and ensures in this way a fixed seal seatof the main filter cartridge 100 in the filter housing 12.

The FIGS. 6-10 show an embodiment of a secondary filter cartridge 200.The secondary filter cartridge 200 comprises a main inflow surface 210,an outflow surface 212 as well as a main flow direction Y1. Moreover,the secondary filter cartridge 200 comprises a filter body 214 which issupported by a filter cartridge frame 216. At the inflow side, thefilter cartridge frame 216 with a frame area 218 circumferentiallysurrounding the filter body 214 is substantially flush with the filterbody 214. The frame area 218 can serve, for example, as an abutment forthe support knobs 128 of the main filter cartridge 100 in the insertedstate of both filter cartridges 100, 200.

In the present embodiment, the filter body 214 is substantiallyparallelepipedal. However, other basic shapes like, for example, a prismare conceivable. At the outflow side, i.e., in the area of the outflowsurface 212, the filter cartridge frame 216 is provided with a gratestructure 220. The grate structure 220 covers the outflow surface 212 atleast partially. In case of a high differential pressure between theinflow side 210 and the outflow side 212, the grate structure 220prevents an undesirable bending or even falling out of the filter body214.

At a narrow side of the parallelepipedal filter body 214, the filtercartridge frame 216 is provided with a grip depression 222. In order toprovide for comfortable gripping in the grip depression 222 by the handof a person who wants to exchange the secondary filter cartridge 200,the frame area 218 in the area of the grip depression 222 is widened toa grip stay 224. The width of the grip stay 224 is selected such in thiscontext that a direct inflow of a fluid exiting from the main filtercartridge outflow side 112 toward the filter body 214 is possible inparticular at the side which is facing the grip depression 222. This iseasily apparent in particular also in the cross-sectional view of FIG.4. Also, from the uppermost edge 113 of the main filter element outflowsurface 112, exiting fluid can flow directly to the filter body 214 ofthe secondary filter cartridge 200. In this context, the fluid can enterin particular through the auxiliary inflow surface 211 into the filterbody 214.

In this embodiment, the filter body 214 is designed as a filter bellows.The fold edges extend in this context parallel to the longitudinal axisof the secondary filter cartridge 200 so that the end faces of the foldsform the auxiliary inflow surface 211. The fold edges of the folds formthe main inflow surface 210 and the outflow surface 212. By thecombination of grip depression 222 and filter bellows 214 with inflowlaterally via the auxiliary inflow surface 211, the pressure losses atthe secondary filter cartridge 200 can be reduced because the secondaryfilter cartridge 200 is matched significantly better to the flowguidance from the main filter cartridge 100 to the outflow socket in thefilter housing 12. At the same time, the grate structure 220 at theoutflow side 212 increases the collapse resistance of the secondaryfilter cartridge 200. Moreover, by means of the integrated grip at thegrip depression 222, an easy removal of the filter cartridge 200 ispossible.

The secondary filter cartridge 200 comprises a filter frame 216 whichprovides a groove 226 extending circumferentially about the outflow-siderim of the filter body 214. At the same time, a web 228 is provided onthe side of the filter cartridge frame 216 which is facing the gripdepression 222. The groove 226 serves as a casting mold for acircumferentially extending adhesive connection and sealing action ofthe filter body 214 with the filter cartridge frame 216. The sealingaction and adhesive connection are effected by a sealing material 230(see FIG. 9). The sealing material 230 can be, for example, a foamingpolyurethane. However, also silicone-based material systems areconceivable.

The groove 226 and additionally the web 228 ensure good mechanicalcoupling of the sealing material 230 on the filter cartridge frame 216.This configuration has moreover the advantage that after introduction ofthe sealing material 230 into the groove 226 and insertion of the filterbody 214 into the filter cartridge frame 216 and a subsequent foamingand hardening, no further processing steps such as, for example, cuttingto size of the sealing material 230, are required. Excess material canbe absorbed partially by the filter body 214 or can reach theintermediate area between filter body 214 and filter cartridge frame 216without this being disadvantageous.

The depth of the groove 226 extends substantially along the main flowdirection Y1 of the secondary filter cartridge 200. The outflow-sidegrate structure 222 can be formed as one part together with the filtercartridge frame 216.

At its inflow-side circumference, the filter cartridge frame 216 has aseal receiving groove 232. In this seal receiving groove 232, a seal 234can be inserted that is, for example, manufactured of cellular rubber.The seal 234 is thus acting radially, i.e., perpendicular to the mainflow direction Y1 of the secondary filter cartridge 200.

FIGS. 15 to 19 show the filter 10 with different orientations of theoutflow socket 26. The filter housing 12 of the filter 10 comprises inthe outflow area 24 a fastening area 25. The fastening area 25 ispositioned relative to the main inflow direction X of the filter housing12 at an angle of approximately 45°. An outflow socket 26 can beattached to the fastening area 25. The outflow socket 26 is shaped suchthat a fluid flowing through the outflow socket 26 is subjected to adeflection of 45°. The outflow socket 26, prior to final attachment onthe fastening surface 25, is rotatably attachable. Accordingly, at avery late point in time in the manufacture of the filter 10 the finaldeflection direction or outflow direction Y of the filter 10 can then bedetermined. In the geometry shown in this embodiment, an inline flow(FIG. 15, FIG. 18), a deflection by 90° (FIG. 17) as well asintermediate angle ranges are possible. In the angle ranges that arebetween the extreme angles, an additional lateral deflection occurs.

What is claimed is:
 1. A filter cartridge for a filter for filtering afluid, the filter cartridge configured to be used downstream of a mainfilter cartridge in a filter, the filter cartridge comprising: a filterbody of filter medium having: an inflow surface on an inflow side of thefilter body; an outflow surface on an outflow side of the filter body; amain flow direction extending from the inflow surface to the outflowsurface; wherein an axial direction, as used herein, is a direction fromthe inflow surface to the outflow surface; wherein a radial direction,as used herein, is a direction traverse to the axial direction; andwherein a lateral radially outer side of the filter body forms anauxiliary inflow surface, the auxiliary inflow surface extending in anaxial direction between the inflow surface and the outflow surface andarranged traverse to the inflow surface; a filter cartridge frame,having an axially extending frame wall radially surrounding radial outersides of the filter body, and extending axially to surround the filterbody from the inflow surface to the outflow surface, the filtercartridge frame comprising: wherein a grip portion of the axiallyextending frame wall at the auxiliary inflow surface slopes radiallyoutwardly away from the filter body, forming a grip depression betweenthe auxiliary inflow surface and the filter cartridge frame; wherein thegrip depression spaces the filter cartridge frame away from the filterbody to allow fluid to radially enter the auxiliary inflow surface; agrip stay formed on the grip portion adjacent to the outflow side of thefilter body; a circumferential seal receiving groove formed on aradially outer side of the filter cartridge frame; a seal arranged inthe circumferential seal receiving groove and configured to separate afilter interior of a filter into a clean side and a raw side; anadhesive connection connecting the filter body and the filter cartridgeframe to each other.
 2. The filter cartridge according to claim 1,wherein the seal is configured to act radially relative to the main flowdirection and wherein the seal extends circumferentially about thefilter cartridge substantially perpendicular to the main flow direction.3. The filter cartridge according to claim 1, wherein the filtercartridge frame comprises a support grate structure forming a pluralityof flow openings, wherein the outflow surface is arranged on andsupported by the support grate structure; wherein the support gratestructure includes a circumferential adhesive groove at the outflow sideof the filter body; wherein an adhesive material is arranged in theadhesive groove, adhesively fixing the filter body to the filtercartridge frame.
 4. The filter cartridge according to claim 3, whereinthe circumferential adhesive groove has a depth and the depth extends ina direction of the main flow direction.
 5. The filter cartridgeaccording to claim 1, wherein the seal receiving groovecircumferentially surrounds externally the filter body.
 6. The filtercartridge according to claim 1, wherein the adhesive connectioncomprises a polyurethane.
 7. The filter cartridge according to claim 6,wherein the adhesive connection partially penetrates the filter body. 8.The filter cartridge according to claim 1, wherein the seal comprises acellular rubber.
 9. The filter cartridge according to claim 3, whereinthe support grate structure is formed as one part together with thefilter cartridge frame.
 10. The filter cartridge according to claim 1,wherein, viewed in the main flow direction, the grip portion and gripdepression substantially does not project past the inflow surface. 11.The filter cartridge according to claim 1, wherein the filter body issubstantially parallelepipedal.
 12. The filter cartridge according toclaim 1, wherein the filter body is a filter bellows and end faces offolds of the filter bellows point in the direction of the grip area;wherein an outermost fold of the filter body forms the auxiliary inflowsurface, extending in an axial direction between the inflow surface andthe outflow surface.
 13. The filter cartridge according to claim 1,wherein the filter cartridge is configured as a secondary filtercartridge.
 14. A filter for filtering a fluid, the filter comprising: afilter housing comprising a raw-side area and a clean-side area; a mainfilter cartridge configured to be arranged in the filter housing,wherein the main filter cartridge comprises a main filter cartridgeinflow surface, a main filter cartridge outflow surface, and a mainfilter cartridge flow direction from the main filter cartridge inflowsurface to the main filter cartridge outflow surface, and wherein themain filter cartridge further comprises a main seal arranged on asealing surface and configured to fluid-tightly separate the raw-sidearea and the clean-side area of the filter housing from each other; asecondary filter cartridge arranged downstream of the main filtercartridge, the secondary filter cartridge comprising: a filter body offilter medium having: an inflow surface on an inflow side of the filterbody; an outflow surface on an outflow side of the filter body; a mainflow direction extending from the inflow surface to the outflow surface:wherein an axial direction, as used herein, is a direction from theinflow surface to the outflow surface; wherein a radial direction, asused herein, is a direction traverse to the axial direction; and whereina lateral radially outer side of the filter body forms an auxiliaryinflow surface, the auxiliary inflow surface extending in an axialdirection between the inflow surface and the outflow surface andarranged traverse to the inflow surface; a filter cartridge frame,having an axially extending frame wall radially surrounding radial outersides of the filter body, and extending axially to surround the filterbody from the inflow surface to the outflow surface, the filtercartridge frame comprising: wherein a grip portion of the axiallyextending frame wall at the auxiliary inflow surface slopes radiallyoutwardly away from the filter body, forming a grip depression betweenthe auxiliary inflow surface and the filter cartridge frame; wherein thegrip depression spaces the filter cartridge frame away from the filterbody to allow fluid to radially enter the auxiliary inflow surface; agrip stay formed on the grip portion adjacent to the outflow side of thefilter body; a circumferential seal receiving groove formed on aradially outer side of the filter cartridge frame; a seal arranged inthe circumferential seal receiving groove and configured to seal to thefilter housing; an adhesive connection connecting the filter body andthe filter cartridge frame to each other wherein the circumferentialseal receiving groove is arranged at a slant to the main filtercartridge flow direction of the main filter cartridge.
 15. The filteraccording to claim 14, wherein the sealing surface and the main filtercartridge flow direction are positioned at an angle relative to eachother that is between 80° and 10°.
 16. The filter according to claim 14,wherein the circumferential seal receiving groove and the main filtercartridge outflow surface extend parallel to each other.
 17. The filteraccording to claim 14, wherein a basic shape of the secondary filtercartridge is a parallelepiped.
 18. The filter according to claim 14,wherein a basic shape of the main filter cartridge is a prism with abase face in the shape of a quadrangle and a top face in the shape of aquadrangle.
 19. The filter according to claim 14, wherein the mainfilter cartridge is a folded bellows with at least two different folddepths.
 20. The filter according to claim 14, wherein the filter housingcomprises an inflow direction, an outflow direction, and an outflow areawith an outflow opening, wherein the filter further comprises an outflowsocket configured to be fastened to the outflow area, wherein theoutflow area comprises a fastening surface for the outflow socket andthe fastening surface is positioned at an angle of 45° relative to themain filter cartridge flow direction.
 21. The filter according to claim20, wherein the outflow socket is shaped such that a deflection of aflow direction by 45° results.
 22. The filter according to claim 20,wherein the outflow socket comprises a fastening area that is embodiedto have rotation symmetry and is configured for attachment to the filterhousing.
 23. The filter according to claim 20, wherein the outflowdirection of the filter housing and the fastening surface are positionedat an angle of 45° relative to each other.
 24. The filter according toclaim 20, wherein the fastening surface and the secondary filtercartridge outflow surface extend parallel to each other.
 25. The filteraccording to claim 14, wherein the main filter cartridge is configuredto be inserted and removed into and from the filter housing along aninsertion axis, wherein the insertion axis is positioned relative to themain filter cartridge flow direction at an angle that is between 90° andthe angle at which the sealing surface is positioned relative to themain filter cartridge flow direction, wherein the filter housingcomprises a cover that is configured such that, in the state in whichthe cover closes off the filter housing, the cover exerts a force on themain filter cartridge in the direction of the sealing surface.